I not sure I'm understanding your problem correctly.

I believe you can't change the brightness of the OVHD/CB yellow/green light brightness using the OVHD and CB brightness knobs. Right?
I was saying that the OVHD/CB light switch doesn't work (at least not for me).

Or is it that you can't turn the yellow/green lights themselves on?
If this is the problem, you have to press the small button in the centre of the MASTER BRIGHT switch, which just to the right of the STORM light switch.